initial check-in, version 0.5.0

src/malloc/__simple_malloc.c

@@ -0,0 +1,44 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <limits.h>
+#include <errno.h>
+#include "libc.h"
+
+uintptr_t __brk(uintptr_t);
+
+#define ALIGN 16
+
+void *__simple_malloc(size_t n)
+{
+	static uintptr_t cur, brk;
+	uintptr_t base, new;
+	static int lock;
+	size_t align=1;
+
+	if (n < SIZE_MAX - ALIGN)
+		while (align<n && align<ALIGN)
+			align += align;
+	n = n + align - 1 & -align;
+
+	LOCK(&lock);
+	if (!cur) cur = brk = __brk(0)+16;
+	if (n > SIZE_MAX - brk) goto fail;
+
+	base = cur + align-1 & -align;
+	if (base+n > brk) {
+		new = base+n + PAGE_SIZE-1 & -PAGE_SIZE;
+		if (__brk(new) != new) goto fail;
+		brk = new;
+	}
+	cur = base+n;
+	UNLOCK(&lock);
+
+	return (void *)base;
+
+fail:
+	UNLOCK(&lock);
+	errno = ENOMEM;
+	return 0;
+}
+
+weak_alias(__simple_malloc, malloc);